helloworld.java

SymbianOS J2ME一书的源码

/*
 * Copyright 2003, 2004 Symbian Ltd.
 * For License terms see http://www.symbian.com/developer/techlib/codelicense.html
 */

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import java.io.IOException;

public class Helloworld  extends MIDlet implements CommandListener {
    
    private MyGameCanvas gameCanvas;
    private MyPauseCanvas pauseCanvas;
    private Command exit;
    private Command pause;
    private Command resume;
    private Display display;
    private Displayable displayable;
    
    public Helloworld() {
        display = Display.getDisplay(this);
        pauseCanvas=new MyPauseCanvas();
        getCanvasDisplay();
        //create the commands for both the gameCanvas and pauseCanvas
        exit=new Command("Exit",Command.EXIT,1);
        pause=new Command("Pause",Command.ITEM,2);
        gameCanvas.addCommand(exit);
        gameCanvas.addCommand(pause);
        gameCanvas.setCommandListener(this);
        
        resume=new Command("Resume",Command.ITEM,2);
        pauseCanvas.addCommand(resume);
        pauseCanvas.setCommandListener(this);
    }
    
    protected void startApp() throws MIDletStateChangeException {
        
        getCanvasDisplay();
        display.setCurrent(displayable);
    }
    
    protected void pauseApp() {
        System.out.println("Pausing...");
        if(displayable!=null) {
            display.setCurrent(displayable);
        }
        releaseResource();
        //notifyPaused();
    }
    
    public void destroyApp(boolean unconditional) {
        releaseResource();
        notifyDestroyed();
    }
    private void releaseResource() {
        if(gameCanvas!=null) {
            gameCanvas.stop();
        }
        
    }
    private void getCanvasDisplay() {
        try {
            if(gameCanvas==null) {
                gameCanvas=new MyGameCanvas(this);
            }
            if(!gameCanvas.isRunning()) {
                gameCanvas.start();
            }
            displayable=gameCanvas;
        }
        catch(IOException ioe) {
        }
    }
    
    
    public void commandAction(Command command, Displayable d)  {
        if (command==exit) {
            destroyApp(true);
        }
        else if (command==pause) {
            displayable=pauseCanvas;
            pauseApp();
        }
        else if(command==resume) {
            try {
                startApp();
                //resumeRequest();
                
            }
            catch (MIDletStateChangeException msce)
            {}
        }
        
    }
    
}